A polysaccharide derivative obtained by modifying the hydroxyl groups or amino groups of a polysaccharide with various substituents is known to serve as a chiral stationary phase in chromatography to show a high optical resolution, and a large number of kinds of polysaccharide derivatives have been heretofore synthesized.
Examples of such polysaccharide derivative useful as a separating agent for optical isomers include: an ester derivative of a polysaccharide (see, for example, Patent Document 1); an alkyl-substituted phenylcarbamate of a polysaccharide except cellulose (see, for example, Patent Document 2); a chitosan derivative (see, for example, Patent Document 3); a cyclodextrin derivative (see, for example, Patent Document 4); a polysaccharide derivative obtained by substituting the hydroxyl groups or amino groups of a polysaccharide with two or more kinds of different substituents (see, for example, Patent Document 5); a polysaccharide derivative obtained by specifically introducing a substituent into the 2-position of a polysaccharide (see, for example, Non-patent Document 1); and a polysaccharide derivative obtained by specifically introducing a substituent into the 6-position of a polysaccharide by the protection of a hydroxyl group at the 6-position by a trityl group and deprotection (see, for example, Non-patent Document 2).
However, a polysaccharide derivative having a specific kind of a substituent at a specific position, in particular a polysaccharide derivative having specific substituents different from each other at its 2- and 3-positions that are hard to distinguish in the introduction of a substituent into a hexose leaves room for future studies.    Patent Document 1: JP 1466384 B    Patent Document 2: JP 1799654 B    Patent Document 3: JP 3041116 B    Patent Document 4: JP 3342482 B    Patent Document 5: JP 3272354 B    Non-Patent Document 1: Cellulose 11: 255-263, 2004    Non-Patent Document 2: Macromol. Chem. Phys. 1996, 197, 953